<s>
In	O
cryptography	O
,	O
New	B-Algorithm
Data	I-Algorithm
Seal	I-Algorithm
(	O
NDS	O
)	O
is	O
a	O
block	O
cipher	O
that	O
was	O
designed	O
at	O
IBM	O
in	O
1975	O
,	O
based	O
on	O
the	O
Lucifer	B-Algorithm
algorithm	O
that	O
became	O
DES	B-Algorithm
.	O
</s>
<s>
Like	O
DES	B-Algorithm
it	O
has	O
a	O
16-round	O
Feistel	B-Algorithm
network	I-Algorithm
structure	O
.	O
</s>
<s>
The	O
round	O
function	O
uses	O
two	O
fixed	O
4×	O
4-bit	O
S-boxes	B-Algorithm
,	O
chosen	O
to	O
be	O
non-affine	O
.	O
</s>
<s>
The	O
nth	O
bit	O
of	O
the	O
output	O
of	O
this	O
table	O
determines	O
whether	O
or	O
not	O
the	O
two	O
nibbles	O
of	O
the	O
nth	O
byte	O
are	O
swapped	O
after	O
S-box	B-Algorithm
substitution	O
.	O
</s>
<s>
Each	O
round	O
function	O
ends	O
with	O
a	O
fixed	O
permutation	B-Algorithm
of	O
all	O
64	O
bits	O
,	O
preventing	O
the	O
cipher	O
from	O
being	O
broken	O
down	O
and	O
analyzed	O
as	O
a	O
system	O
of	O
simpler	O
independent	O
subciphers	O
.	O
</s>
